Recently, there has been significant research focusing on vehicular four wheel steering technology. A vehicle equipped with a four wheel steering system benefits from improved performance on almost any road surface over vehicles without such systems. Existing steering control systems are disclosed in U.S. Pat. Nos. 4,740,002, 5,035,295 and 5,048,633.
Even with an existing 4WS system, a vehicle can experience directional instability during accelerations and decelerations on slippery road surfaces (i.e. low .mu. road surfaces, such as snow). It would therefore be desirable to improve the handling of both front wheel drive and rear wheel drive cars on low .mu. road surfaces by combining traction control with a 4WS system. By doing so, lateral deviation error can be minimized, which would increase vehicle stability while performing certain maneuvers.